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An amendment to this paper has been published and can be accessed via the original article.

Tamara Grummt passed away on January 26, 2020 in Oelsnitz/Vogtland, Germany. Tamara was one of the scientific pioneers in the field of environmental toxicology, namely genotoxicity and hygiene of drinking and bathing waters. Her passing is not only a great loss to environmental research and to the global environmental toxicology community—we have lost an outstanding personality with the heart in the right place, who has become, for many of us, a wonderful friend.

The present study explained the inhibitory effect of natural organic matter (NOM) on the photocatalytic degradation of clofibric acid (CA), and attempted to eliminate this inhibition by changing reaction conditions. The NOM degradation was followed by size-exclusion chromatography for dissolved organic carbon and ultraviolet absorption (SEC-DOC and SEC-UV254).The results demonstrated that the deactivation of NOM on catalyst was more dependent on the molecular weight of NOM than on its concentration. Higher molecular weight fractions were prone to adsorb onto the catalysts’ surface and acted as electron-hole scavengers and light filters to reduce the photocatalytic degradation rate of CA. pH adjustment changed the adsorption property of NOM, while, decreasing of its inhibition was not observed. However, the oxygen addition can significantly eliminate this inhibitory effect by increasing the degradation rate of high molecular size fractions of NOM.

The influence of ionic strengthen and dissolved organic matter (DOM) on the aggregation of TiO 2 nanoparticles (NPs) in municipal effluent was investigated. The results demonstrated that DOM promoted the mobility of NPs in aquatic system by synergism between static repulsion and steric effect, while electrolytes were opposite by charge-neutralization. The physical-chemical characteristics of DOM played the major role on the mobility of NPs. Bovine serum albumin (BSA) showed the strongest enhancement on the mobility of TiO 2 NPs. High adsorption of BSA introduced vast negative charges on the TiO 2 NPs’ surface, leading to static repulsion and neutralizing positive charges of electrolytes in surrounding as well. By contrast, another protein α-amylase retarded the aggregation rate of TiO 2 NPs through steric repulsion of the long-chain construction. Humic substances (Fulvic acid and alginate) also reflected the combination of static repulsion and steric effect. However, in the high electrolytes concentration (especially Ca 2+ ), the long-chain aliphatic compounds were prone to form calcium bridge which increased the hydrodynamic diameter of TiO 2 aggregates consequently. Sodium dodecylbenzene sulfonate (SDBS) showed low adsorption capacity, while the unabsorbed SDBS retarded the aggregates caused by the changes of pH and electrolytes. These data indicated that decreasing of DOC concentration in aqueous system was important to reduce the mobility and potential risk of NPs in aqueous system.

The W0-factor is a common metric to express the aggressivity of water against unalloyed iron. It accounts for multiple parameters, called rating numbers, which represent the concentration of chloride, sulfate and calcium ions, the pH-value and the acid capacity of the immersion medium. The use of ranges in the physical quantities metric rating number, however, allows for unaccounted variations in the immersion medium composition, i.e., slightly different immersion media may produce the same W0-factor. To verify the results, the experiments were also carried out with natural waters as immersion media and their W0-factors were determined. In addition, the DOC content, which is not included in the W0-factor, has an impact on the corrosive character of the immersion medium. In order to account for the influence of the DOC content in the measurements, multiple solutions with different DOC concentrations were investigated. The results show that a higher DOC content (based on humic substances) in the observed solutions causes a reduction in the corrosion rate. This result agrees with observations of nature.

Generally, corrosion rates for sheet pile walls observed in nature and those obtained in the laboratory are different. In order to compare natural and laboratory corrosion rates, corrosion tests were carried out with an electrochemical corrosion cell. Various mild steel samples which were taken out from different sheet pile structures were examined with synthetic brackish water and synthetic seawater as immersion media. It was ensured that the electrical conductivity and the pH-values were identical to those of the natural waters from which the sheet pile samples came from. The experimental results indicate that underwater corrosion rates in nature are only about one tenth to one eighth of the laboratory values. The corrosion rates in nature depend on the media and the corrosion zone. Furthermore, in laboratory test procedures, the initial corrosion is always tested whereas in nature a “protecting” layer of rust is formed, that lowers corrosion. Therefore, comparison of the values of the experiments with those from nature should be defined in accordance to age and zone of hydraulic steel structures. As a consequence, a corrosion coefficient with consideration of the age of structures was formed. The introduction of the coefficients's dependence on the lifetime of the construction allows improved corrosion rate predictions when the chemical composition of the immersion media is detected.

In this work, the photocatalytic generation of free OH radicals ( OH free ) in aqueous TiO 2 suspensions was studied using an 18 O isotope labeling and a “remote” photocatalysis approach. A probe compound, 1,3,5-trichlorobenzene (TCB), was adsorbed in pores of silica gel (SG) microparticles and, by this, was shielded from the direct hole oxidation. Penetration of the TiO 2 particles (25 nm in size) to the TCB, adsorbed in the SG pores, was blocked due to a small size of the SG pores (4 nm). Therefore, the “remote” degradation of the TCB was solely driven by OH free , and this allowed us to selectively determine the quantum yield of the OH free generation. The isotope labeling with 18 O has demonstrated that the major pathway of the OH free formation is the direct hole oxidation of H 2 O, whereas the reduction of dissolved O 2 by photogenerated electrons contributes in less than 5% of the total amount of OH free . Nevertheless, the latter pathway becomes more important if holes are scavenged. This work sheds light on the intrinsic roles of photogenerated holes and electrons in the mechanism of the OH free formation in aqueous TiO 2 photocatalysis.

Natural organic matter (NOM) is ubiquitous in aquatic environment, which plays a predominant role in the sorption of pharmaceuticals onto the TiO 2 nanoparticles. It is a matter of concern whether NOM could act as a surface sensitizer of TiO 2 or not. In this context, the role of NOM is investigated for the photocatalytic degradation of carbamazepine (CBZ) using TiO 2 . Four different ratios of NOM:TiO 2 were used varying from 400 μg g −1 to 400 mg g −1 . The findings reveal that small amounts of NOM could enhance the TiO 2 efficiency up to 8%. Electron paramagnetic spectroscopy (EPR), along with size exclusion chromatography with dissolved organic carbon detection (SEC-OCD) and nuclear magnetic resonance spectroscopy (NMR) reveal the occurring mechanism. TiO 2 binds small molecular size fractions of NOM and breaks aromatic bonds of adsorbed NOM transforming it to stranded alkyl groups. This modified TiO 2 bears a significant amount of electrons (e − ) and lesser holes (h + ) than the purified TiO 2 and when irradiated, produces hydroxyl radicals which degrade CBZ.

The tremendous generation of solid waste material is a worldwide problem. Apart from avoidance of waste materials, their reuse is a main goal of modern waste management. Reuse of waste materials demands adequate risk assessment and reliable quantification methods considering the release potential of harmful compounds. In this context, due to its cancerogenity, hexavalent chromium (Cr(VI)) is of high ecotoxicological, human toxicological and environmental relevance. In this contribution, we focus on the speciation of chromium in two representative solid waste materials (demolition waste material, DWM; municipal waste incineration product, MWIP) and eluates obtained after leaching. For chromium speciation, X-ray absorption spectroscopy (XAS) and ion chromatography coupled with inductively coupled plasma optical emission spectrometry (IC/ICP-OES) were applied. It could be observed that in spite of relatively low contents of Cr(VI) in both solid materials (DWM: 16 ± 1 mg/kg, MWIP: 67 ± 5; aqua regia digestion), environmentally relevant concentrations of Cr(VI) were released from the materials as revealed by batch and column leaching experiments. In particular, threshold values for Cr(VI) of the German Federal Soil Protection and Contaminated Sites Ordinance were significantly exceeded. Application of XAS allowed both the determination of mobilizable Cr(VI) directly in the solid materials and in the alkaline eluates, even at concentrations below 500 µg/L. The results obtained were in agreement with data of leaching tests and with IC/ICP-OES measurements. IC/ICP-OES enabled a rapid, well-reproducible and sensitive quantification of Cr(VI) in the eluates in the lower µg/L range. The presented combination of independent analytical methods and mutual validation is highly powerful and is a valuable contribution for risk assessment of waste material. The principle of the approach can be used for the investigation of other solid materials and elements and their assessment.

In this study, a hazardous DNA-binding agent, bisphenol A 3,4-quinone (BPAQ), was detected among products of bisphenol A (BPA) photocatalytic degradation. To clarify the mechanism of BPAQ formation, we investigated BPA degradation by TiO 2 photocatalysis and UV photolysis at 254 nm in detail. The main focus was given to understanding the roles of OH radicals and photogenerated holes in the evolution of potentially harmful aromatic products. Five new intermediates were identified using an enhanced LC–MS–MS/ToF approach. We found that direct hole oxidation was abundantly responsible for the transformations of BPA into quinone and catechol products. Scavenging of free OH radicals induced a mechanism change and intensified BPAQ formation. Direct UV photolysis produced two catechol derivatives with potentially lower endocrine-disrupting activity in comparison to BPA. Both of the processes demonstrated similar efficiencies in BPA elimination. Complete mineralization was achieved only in the case of TiO 2 photocatalysis, but accompanied by potentially genotoxic intermediates formed by hole oxidation.

A simplified model of environmental conditions was developed to evaluate the effect of natural organic matter (NOM) and metal ions on the Pt/TiO2 photocatalytic degradation of diatrizoate and I - formation in the presence of different dissolved oxygen (DO) level. The results showed that the photocatalytic degradation of diatrizoate was strongly influenced by the amount of DO present and by the presence of metal ions. The DO concentration and the presence of NOM severely affected the formation of I - . The high R 2 values of the model signify that the models obtained are able to give a reasonably good estimate of response for the system in the range studied.

Reservoir water becomes increasingly important as a drinking water resource in densely populated areas that have to respond to the challenge of water scarcity and quality. The Lake Paranoa in Central Brazil is under discussion to be used as a reservoir for drinking water production. There is concern regarding the water quality since the two largest wastewater treatment plants discharge into the lake. This issue raised the question about the need and efficiency of additional treatment to remove micropollutants. In this context, the present study aims to derive decision-making support by estimating the future concentration trends of five selected micropollutant markers in Lake Paranoa based on a minimum measured data set of three years. Results indicated slowly increasing trends and no steady-state situation until 2060 for persistent compounds. A quasi steady state is reached for degradable micropollutants. Furthermore, scenario analyses showed that a reduction of micropollutant emissions by advanced wastewater treatment would only be observable and detectable in the lake after around one decade due to the inertia of the lake. This agrees well with the observed total phosphorus reduction after the installation of phosphorus removal treatment.

Im Rahmen der Erdgasforderung soll in Deutschland vermehrt das hydraulische Fracking eingesetzt werden. In der Offentlichkeit bestehen grose Besorgnisse und Zweifel bzgl. der Sicherheit dieser Technik. Kritisch gesehen wird insbesondere die Gefahr einer Kontamination des Grundwassers und des Trinkwassers. In dem vorliegenden Beitrag werden die Risiken der Fracking-Technologie in Bezug auf eine mogliche Kontamination des Grundwassers erortert. Im Vordergrund steht die toxikologische Bewertung der beim Fracking eingesetzten Hilfsstoffe (Additive), die im Falle eines Storfalls im Grund- und Trinkwasser auftreten konnten. Aufgrund der in Deutschland bestehenden Sicherheitsanforderungen und im Hinblick auf die vor jedem Frac erforderliche geologische und hydrogeologische Standortprufung wird das Risiko einer Kontamination des Grundwassers und des Trinkwassers durch Additive von Frack-Flussigkeiten als gering eingeschatzt. Bei zukunftig durchzufuhrenden Fracs sollte ein Grundwasser-Monitoring obligatorisch sein. In die Genehmigungsverfahren fur Fracs, die bisher allein von den Bergbehorden durchgefuhrt werden, sollten zukunftig auch die zustandigen Wasserbehorden eingebunden werden. In Wasserschutzgebieten sollte grundsatzlich auf das Fracking verzichtet werden.

Application of nanofiltration (NF) membranes has increased during the last years: many industries from drinking water treatment and water re-use to the pharmaceutical and food industry deal with the application of NF and its drawbacks. One of the main problems of membrane technology is fouling. Fouling during NF is a complex problem because of the importance of the membrane surface properties (e.g. charge and structure) and the corresponding interactions between the water constituents and the membrane. In this work, the fouling layer composition of three membranes was investigated using different raw waters and it was correlated with the membrane performance. Rejection properties depended to a great extent on the water composition and the ionic strength of the raw water. Investigations of fouling layer compositions suggest that the membrane properties play a key role for flux decline and the related “amount” of fouling material on the membranes and its constituents.

This paper deals with the possible impact of hydraulic fracturing (fracking), employed in the exploitation of unconventional shale gas and tight gas reservoirs, on groundwater, which is the most important source of drinking-water in Germany and many other European countries. This assessment, which is part of an interdisciplinary study by a panel of neutral experts on the risks and environmental impact of hydraulic fracturing, is based mainly on data obtained from three ExxonMobil drilling sites in northern Germany. First, the basic technical aspects of fracking and its relevant water fluxes are explained. The type, purpose and fate of the constituents of the fracking fluids are discussed. The chemicals used in the fracking fluids are assessed with regard to their hazardous properties according to the Regulation (EC) No. 1272/2008 of the European Parliament and of the Council on the classification, labelling and packaging of substances and mixtures (CLP regulation) and the German “Water Hazard Classes”. Contamination of groundwater by ingredients of fracking fluids may occur from under ground or may result from above-ground accidents associated with the transport, storage and handling of hazardous substances used as additives in fracking fluids. The degree of groundwater contamination cannot be predicted in a general way. Therefore, different dilutions of the fracking fluid in groundwater are considered. It is shown that the concentrations of most ingredients resulting from a 1:10,000 up to 1:100,000 dilution of the fracking fluid in groundwater are below health-based reference values such as the limit values of the European Drinking Water Directive, the WHO Guideline Values for Drinking-water Quality, and other health-based guide values for drinking-water. Regarding the salinity of fracking fluids, a dilution of 1:1,000 is sufficient to reach concentrations which are acceptable for drinking-water. From the human-toxicological point of view, the constituents of flowback water are more problematic with respect to drinking-water produced from groundwater than those of the fracking fluids. The few reliable data which have become available, as well as hydrogeological considerations, point in the direction of considerable salt concentrations and toxic constituents, e.g., Hg, As, Pb, Zn, Cd, BTX, PAHs, or even radioactive elements. The identification and assessment of reaction products and metabolites, which are produced as a result of the fracking operation and the metabolic activity of microorganisms, are important topics for further research. The recommendations include the need for a better understanding of the environmental impact of fracking operations, especially with regard to the development of sustainable rules for planning, permission, performance and management of fracking, and for the monitoring of groundwater quality around fracked drilling sites.

A photocatalytic disinfection with P25 TiO(2) was conducted at three pH-values (4, 7 and 10) in NaCl solution (c = 10 mmol L(-1)). Neither the osmotic stress nor solely the pH-value had a significant impact on the survival of the Escherichia coli cells. The cells were more damaged at pH 4 than at pH 7 and 10 in irradiation experiments with TiO(2). The smallest disinfection rates occurred at pH 10. SEM images revealed that the surface of the cells was covered with TiO(2) to a greater extent at pH 4 compared to pH 10. At pH 10, the disinfection rates increased when increasing the ionic strength and changing the NaCl solution to CaCl(2). The results indicate that the disinfection rates depend on the electrostatic interaction between cells and TiO(2). The differences could be qualitatively better explained by the XDLVO theory in comparison to the DLVO theory.

This study reports the use of excitation-emission matrix (EEM) fluorescence and UV/Vis spectroscopy to monitor the changes in the composition and reactivity of Aldrich humic acids (Aldrich HA) as a model compound for natural organic matter (NOM) during photocatalytic degradation. Degussa P-25 titanium dioxide (TiO(2)) and a solar UV-light simulator (a batch reactor) were used. The photocatalysis shifted the fluorescence maxima of EEMs of Aldrich HA toward shorter wavelengths, which implied that the photocatalytic degradation of commercial Aldrich HA caused the breakdown of high molecular weight components and the formation of lower molecular weight fractions. In addition, the fluorescence intensity of fulvic- and humic-like Aldrich HA presented a strong correlation with dissolved organic carbon (DOC), specific UV absorbance (SUVA) parameters, trihalomethane formation potential (THMFP), and organically bound halogens absorbable on activated carbon formation potential (AOXFP). Fluorescence spectroscopy was shown to be a powerful tool for monitoring of the photocatalytic degradation of HA.

The article contains sections titled: 1. Properties of Pure Water 1.1. Molecular Properties 1.1.1. Isotopic Composition 1.1.2. The Water Molecule 1.1.3. Hydrogen Bonding and Water Structure 1.2. The Phase Behavior of Water 1.2.1. Invariant Points 1.2.2. Liquid-Vapor Equilibria 1.2.3. Solid-Liquid and Solid-Solid Equilibria 1.2.4. Supercooled Water and Amorphous Ice 1.3. Properties of Liquid and Supercritical Water 1.3.1. Water over Wide Ranges in Temperature and Pressure 1.3.2. Equation of State and Volumetric Properties 1.3.3. Thermodynamic Properties 1.3.4. Transport Properties 1.3.5. Surface Tension 1.3.6. Auto-protolysis 1.3.7. Dielectric Properties 2.2.2. Transport Properties 2. Water as a Solvent 2.1. Solvent Properties of Water 2.2. Solutions of Nonpolar Gases and Hydrophobic Species 2.3. Hydrophilic Solutes 2.4. Electrolyte Solutions 2.5. Supercritical Water as a Solvent 3. Water Analysis 3.1. Sampling and Sample Preservation 3.2. Physicochemical and Sum Parameters 3.3. Inorganic Analysis 3.3.1. Determination of Cations 3.3.2. Anion Analysis 3.3.3. Determination of Dissolved Gases 3.3.4. Rapid Tests 3.4. Organic Analysis 3.4.1. Spectrometric Methods 3.4.2. Gas and Liquid Chromatography 3.5. Bioanalytical Methods 4. Hydrological Cycle and Water Use 4.1. World Water Balance 4.2. Hydrological Cycle 4.3. Demand for Water 4.4. Source of Water Used 4.5. Water Treatment

The combination of ultrafiltration (UF) and powdered activated carbon (PAC) has gained in importance over the last 15 years. The aim of applying PAC-UF hybrid processes is to improve the rejection capacity and the performance of membrane processes. In this work the influence of PAC-addition on membrane flux decline and fouling formation was studied with a submerged module using different water matrices. The PACs used were characterized by measurements of the surface area, the particle size distribution and the surface charge to get a better understanding of the observed effects. Results showed that the membrane flux decline was dependent on the applied type of activated carbon. When adding Picachem 8P, the transmembrane pressure (TMP) increased very quickly and the membrane performance was even worse than that without PAC. However, when adding Norit SA-UF under identical filtration conditions, the TMP was stable and the membrane performance was better than that without PAC. The fouling layers of the two PACs applied showed entirely different structures. Therefore the selection of a suitable PAC is a main factor for the overall performance of PAC-UF hybrid systems with submerged membranes.

Much research has been undertaken on the photocatalytic degradation of humic substances with titanium dioxide using commercial humic acids (HA), which are extracts from either peat or coal. Most of the research has been focused on the changes in dissolved organic carbon (DOC) and UV254 absorption. These parameters only give a general assessment. This work studies the changes in the physical and structural properties of a commercial humic acid by size exclusion chromatography with DOC and UV254 absorption detection (SEC-DOC, SEC-UV254), and the evolution of halogenated organic compounds (AOX) and trihalomethanes (THMs) during the photocatalytic degradation with simulated solar UV irradiation and Degussa P-25 TiO2. These changes are compared with those reported for natural organic matter (NOM). The photodegradation of commercial HA and NOM proceeds in a similar and sequential manner, initially with the preferential adsorption of larger molecules, then the degradation of these larger molecular size fractions and proceeding towards smaller molecular size fractions, while decreasing THMs and AOX formation potential.

Nanoparticles (NP) are ubiquitous in environmental and technical aquatic systems. Understanding the role and the fate of NP in these systems is an interdisciplinary challenge requiring innovative experimental, theoretical and analytical approaches and critical reflection of classical concepts. This contribution critically reviews the outstanding properties of NP and the resulting consequences for their behaviour in environmental and technical aquatic systems considering natural NP which are mostly geogenic or biogeogenic, and engineered NP. Owing to the severe lack of data on the occurrence of NP in environmental aquatic systems, it is a key task of researchers to further develop analytical methods for the sensitive detection of NP directly in aqueous samples. There is urgent need for standardisation of analytical methods for detection and characterisation of NP, and for toxicity tests to assess possible adverse effects of NP. In this context, NP reference materials have to be defined as a common fundament for research in this field.

Land-use/cover change (LUCC) and climate change are major controlling factors for water resources in the Distrito Federal in Western Central Brazil. Dynamic LUCC in the region has severe impacts on water resources, while climate changes during the last three decades is thought to have only moderate effects. LUCC affects water quantity mostly during base flow conditions. River basins with substantial expansion of agriculture since the end 1970s show a dramatic decrease of base flow discharge by 40–70%, presumably due to irrigation. In contrast, the effects of urbanization on runoff are less distinct, since factors controlling runoff generation might be more variable. For water quality, we found urban areas to have a strong influence on the parameters CSB, NH4+, and suspended solids. In addition, we assume emerging pollutants, e.g. organic (micro)pollutants, might play a major role in the future. The project IWAS-AGUA DF focuses on creating the scientific base to face these problems in frame of an IWRM concept for the region. Results of our study will be a contribution to an IRWM concept for the Distrito Federal and will help to maintain high standards in water supply for the region.

In this study an in vitro exposure test to investigate toxicological effects of the volatile disinfection by-product trichloramine and of real indoor pool air was established. For this purpose a set-up to generate a well-defined, clean gas stream of trichloramine was combined with biotests. Human alveolar epithelial lung cells of the cell line A-549 were exposed in a CULTEX® device with trichloramine concentrations between 0.1 and 40 mg/m3 for 1 h. As toxicological endpoints the cell viability and the inflammatory response by the cytokines IL-6 and IL-8 were investigated. A decreasing cell viability could be observed with increasing trichloramine concentration. An increase of IL-8 release could be determined at trichloramine concentrations higher than 10 mg/m3 and an increase of IL-6 release at concentrations of 20 mg/m3. Investigations of indoor swimming pool air showed similar inflammatory effects to the lung cells although the air concentrations of trichloramine of 0.17 and 0.19 mg/m3 were much lower compared with the laboratory experiments with trichloramine as the only contaminant. Therefore it is assumed that a mixture of trichloramine and other disinfection by-products in the air of indoor pool settings contribute to that effect.

Trichloramine is a volatile, irritant compound of penetrating odor, which is found as a disinfection by-product in the air of chlorinated indoor swimming pools from reactions of nitrogenous compounds with chlorine. Acid amides, especially urea, ammonium ions and α-amino acids have been found as most efficient trichloramine precursors at acidic and neutral pH. For urea a relative NCl(3) formation of 96% at pH 2.5 and 76% at pH 7.1 was determined. Even under sub-stoichiometric molar ratios of Cl/N the formation of NCl(3) is favored over mono and dichlorinated products. However, the reaction kinetics of urea with chlorine is slow under conditions relevant for swimming pools. Also the mass transfer of NCl(3) from water to the gas phase which was calculated by the Deacon's boundary layer model could be shown as a relatively slow process. Mass transfer would take 20 h or 5.8 d for a rough or a quiescent surface of the water, respectively. This is much more than a typical turnover rate of 6-8 h of a treatment cycle of a 25 m swimming pool. Therefore processes to remove NCl(3) and its precursors can help to minimize the exposure of bathers.

Anaerobic degradation processes play an important role in contaminated aquifers. To indicate active biodegradation processes signature metabolites can be used. In this study field samples from a high-resolution multilevel well in a tar oil-contaminated, anoxic aquifer were analyzed for metabolites by liquid chromatography-tandem mass spectrometry and time-of-flight mass spectrometry. In addition to already known specific degradation products of toluene, xylenes, and naphthalenes, the seldom reported degradation products benzothiophenemethylsuccinic acid (BTMS), benzofuranmethylsuccinic acid (BFMS), methylnaphthyl-2-methylsuccinic acid (MNMS), and acenaphthene-5-carboxylic acid (AC) could be identified (BFMS, AC) and tentatively identified (BTMS, MNMS). The occurrence of BTMS and BFMS clearly show that the fumarate addition pathway, known for toluene and methylnaphthalene, is also important for the anaerobic degradation of heterocyclic contaminants in aquifers. The molar concentration ratios of metabolites and their related parent compounds differ over a wide range which shows that there is no simple and consistent quantitative relation. However, generally higher ratios were found for the more recalcitrant compounds, which are putatively cometabolically degraded (e.g., 2-carboxybenzothiophene and acenaphthene-5-carboxylic acid), indicating an accumulation of these metabolites. Vertical concentration profiles of benzylsuccinic acid (BS) and methyl-benzylsuccinic acid (MBS) showed distinct peaks at the fringes of the toluene and xylene plume indicating hot spots of biodegradation activity and supporting the plume fringe concept. However, there are some compounds which show a different vertical distribution with the most prominent concentrations where also the precursor compounds peaked.

The King Abdullah Canal (KAC) is an artificial water conveyor serving as raw water source for drinking water supply of Amman and for irrigation purposes in the Jordan Valley. The main water sources for KAC originate from the Yarmouk River, the Mukheiba Wells, and the Peace Conveyor. Water samples were collected from December 2002 to May 2004 to investigate changes in physicochemical parameters and parameters related to eutrophication along KAC. The catchment area of KAC is highly heterogeneous in terms of topography, climate, geologic conditions, and land use, resulting in great variations in the physicochemical composition of the canal water. The Yarmouk River and the Mukheiba Wells reflect the water quality of precipitation without much dissolution of halides, whereas the Peace Conveyor shows a groundwater characteristic. Main dischargers of N and P compounds are the Yarmouk River, and dams and wadis along KAC. The concentrations in the canal are mostly above eutrophication level for N and P. Along KAC ...

In this work, the interaction of natural organic matter (NOM) with metal(loid)s (Cu, Pb, Zn, Pt, As) and the role of NOM on the metal(loid) transport in a water-saturated quartz sand column were investigated. For detailed information, size exclusion chromatographic (SEC) measurements and “short pulse” laboratory transport experiments with online metal(loid) and NOM detection were used. The SEC measurements showed the formation of metal–NOM complexes. Cu, Pb, Zn and Pt were predominantly bound to the high molecular mass NOM molecules. The binding capacity of the NOM for metals increased with increasing pH value and in the following order: Zn < Pb < Cu < Pt. No evidence for the formation of As–NOM complexes was found. The transport experiments showed no significant influence of NOM on the mobility of Cu, Pb and Zn. The metal–NOM complexes detected in the SEC experiments were obviously sorbed completely onto the grain surfaces in case of the quartz sand system, or they were dissociated partially during passage through the column. No influence of NOM was observed on the transport of As as well. Inorganic Zn and As species were transported through the column with increasing retardation as the pH value increased. Pt showed a high mobility at a pH of 5, and it decreased at a pH of 7 especially in the presence of NOM. The results support the known fact that a decrease in the pH value results in enhanced transport of inorganic metal(loid) species in water-saturated porous media. On the other hand, the presence of NOM can immobilise the metals through metal–NOM complex formation and the deposition of the complexes onto the stationary phase.

We report the formation of bromoform in TiO(2) suspensions (P25) under simulated solar UV irradiation at different concentrations of photocatalyst (0.5-1.5 g L(-1)) as well as initial concentrations of bromide ions (1-3 mg L(-1)) and 2,4-dihydroxybenzoic acid (2-10 mg L(-1)). The extent of bromoform formation (3-17 mu g L(-1)) was most strongly affected by the amount of photocatalyst present and by the initial bromide concentration, increasing either of which leads to increased bromoform formation. Important interaction effects were observed when simultaneously increasing the concentrations of TiO(2) and bromide as well as of bromide and DHBA. The time it takes for bromoform. to appear in measurable concentrations in the irradiated TiO(2) suspensions was between 10 and 90 min and most strongly depended on the initial concentration of dissolved organic carbon present in the suspensions, along with the amount of photocatalyst, also in interaction with the initial bromide concentration.

Herein we report on the photocatalytic degradation of natural organic matter from a bog lake (Lake Hohloh, Black Forest, Germany) as followed by size exclusion chromatography with dissolved organic carbon (DOC) and ultraviolet ( λ = 254 nm) detection (SEC-DOC and SEC-UV). When irradiating this humic-rich water in the presence of 0.5 g L−1 titanium dioxide (P25), we found a preferential degradation of the higher molecular weight DOC fraction. This was coupled to growth of the middle and small DOC fractions. Mineralization proceeded in two distinct steps: a first stage without noticeable mineralization, followed by a phase of steady decrease in dissolved organic carbon. Formic, oxalic, succinic and glutaric acids were found in the irradiated samples and contribute significantly to the bioavailable DOC after irradiation, which favors bacterial regrowth.

The evaluation of the molecular size distribution of natural organic matter (NOM) in aquatic environments via size exclusion chromatography (SEC) is important for the understanding of environmental processes such as nutrient cycling and pollutant transport as well as of technical water treatment processes. The use of organic carbon (OC) detectors has become popular in recent studies due to improved availability and quantification possibilities, which supposedly are superior to those of ultraviolet (UV) detectors. A set of 12 NOM samples was used to demonstrate the limitations of online OC detection (OCD) when analyzing complex aquatic organic matter. A novel evaluation approach for SEC data is introduced by combining the information from UV absorbance (UVA) and OCD chromatograms as well as offline total OC (t-OC) and dissolved OC-specific UVA (SUVA) measurements. It could be shown that about 70% of certain OC components were not detected with the OCD system used in this study. For the investigated samples, these types of carbon accounted for up to 72% of the t-OC, i.e. for such NOM samples quantification by OCD is not possible or at least highly questionable. The addition of an oxidant improved the overall oxidation efficiency only slightly. Most likely NOM that predominantly consists of polysaccharides and features a nominal molecular weight of 150 kg/mol or more was responsible for low OCD yields. For future applications, a further improvement of the OCD system would be worthwhile so that quantitative analytical data on the molecular size distribution of NOM and its structural characteristics such as the SUVA distribution can be obtained.

The efficiency of binding during enzyme immobilisation does not only depend on the chemical properties of the enzyme and the matrix particle, but also on their surface potential. Zeta potential quantifies the electrostatic interactions between enzyme and matrix particles, and can therefore, be used as an indicator of the binding efficiency in the enzyme immobilisation studies. In order to establish a correlation between the zeta potential and the binding efficiency, we used CALA (Candida antarctica A-type lipase) as a model protein for immobilisation on non-porous magnetic microparticles with epoxy (M-PVA E02), carboxy (M-PVA C12) and amine (M-PVA N12) terminations. We observed maximal binding of CALA onto the M-PVA N12 beads, due to the electrostatic attraction between negatively charged protein and carrier particles with slightly positive zeta potential. The binding of CALA was lower when M-PVA E02 beads were used, followed by M-PVA C12 beads. The decreasing binding efficiency was obviously the result of increasing electrostatic repulsion between the interaction partners. This could be correlated to the increasing negative zeta potential of the magnetic particles. Moreover, the medium of suspension of the particles also makes a significant difference. We found highest specific activity of the lipase immobilised on M-PVA E02 beads in a medium concentrated buffer (0.3 M). The results demonstrate a clear correlation between zeta potential and binding efficiency but no correlation between the bead related specific activity and the zeta potential. These findings are advocating the possibility of using the zeta potential as a diagnostic tool in enzyme immobilisation.

We investigated the release of chloride, sulfate, sodium, copper, chromium, and dissolved organic carbon from a demolition waste material and a municipal waste incineration product Batch leaching tests at the liquid-to-solid ratios (L/S ratios) 1, 2, 5, 10, and 50 L kg(-1) were carried out and the parameters of a mass balance-partitioning model were estimated from measured concentrations in the extracts by applying a Bayesian approach using a Markov Chain Monte Carlo sampler. We assessed the uncertainty of the model parameters, the desorption isotherms, and the model-predicted concentrations, respectively. Both the excellent fit to the experimental data and a comparison between the model-predicted and independently measured concentrations at the L/S ratios of 0.25 and 0.5 L kg(-1) showed the applicability of the model for almost all studied substances and both materials. Since experimental difficulties impede extraction tests at L/S ratios representative of field soil-water contents, the predictability of concentrations in this range is of great practical relevance for risk assessments. We conclude that batch extraction tests at varying L/S ratios provide, at moderate experimental cost, a powerful complement to established test designs like column leaching or single batch extraction tests.

The application of membrane filtration in the treatment of spent filter backwash water (SFBW) permits efficient removal of microorganisms, suspended particles and organic substances, depending on the used membrane molecular weight cut-off. However, flux decline, due to deposits and adsorption of substances (salts, colloids, organics, particles, microorganisms, etc.) tends to limit the use of membranes. Characterization of SFBW samples from different waterworks showed that three major factors contribute to the SFBW properties: the raw water itself, the time interval of sand filter operation and additional treatment steps. The main differences between SFBW samples were found principally in DOC, TOC and turbidity. Experiments with submerged membranes (lab- and pilot- scale modules) showed that there was a clear correlation between DOC concentration of the feed and the flux decline: when the DOC-concentration increased, the flux decline increased. Additionally, the presence of calcium led not only to an important flux decline but to high adsorption of NOM on the membrane surface. Iron concentrations in the micromolar range resulted in a considerably decline of flux. Filtration of SFBW revealed that the decline of permeability is mainly determined by DOC, calcium and iron concentrations. A decisive effect of biofouling on membrane performance is expected for long term experiments.

The effects of four different filtration modes (i.e. relaxation, backwash, mixed and continuous) producing the same flux productivity (time average flux) on membrane fouling were investigated in membrane bioreactors (MBRs). The fouling behaviour was found to be strongly dependent on the applied instantaneous flux rather than the filtration modes themselves. The transmembrane pressure (TMP) obtained after 24 h of filtration was dominated by the fouling rates calculated within the first hour of the experiment. After the filtration experiments, the resulting fouling layers were fractionated by rinsing, backwashing and then chemical cleaning, with the foulant removal reflecting the strength of attachment to the membrane. An analysis of the three different fouling layers provided a unique insight into the composition (protein and carbohydrate) and spatial distribution of the particulate and soluble foulants. The upper fouling fraction consists of a porous, loosely bound cake layer with a similar composition to the biomass flocs. The intermediate fraction, which consists of equal parts of soluble molecular products (SMP) and biomass aggregates, features a higher concentration of carbohydrates and possibly plays a significant in the formation of consecutive cake layer. The lower fraction, representing the irreversible fouling fraction and predominantly consisting of SMP, features a relative higher concentration of strongly bound proteins. Whereas the lower and the intermediate fractions showed similar properties for all filtration modes, the upper fraction was influenced by the instantaneous flux.

The impact of selected pollutants on the structure and activity of nitrifying bacterial populations within fixed bed biofilm reactors was examined. Clofibrinic acid and ibuprofen as pharmaceutically active compounds were added to a synthetic wastewater fed to the biofilm reactors and the concentrations of chloride and dissolved organic carbon were also varied. Clear impacts of increased salt and dissolved organic carbon concentrations on nitrification activity and nitrifying bacterial populations were observed whereas clofibrinic acid (up to 100 µg/l) and ibuprofen (10 µg/l) showed no impact on the nitrification activity. The exposure to clofibrinic acid also showed no significant influence on the nitrifying bacterial population, while the addition of ibuprofen resulted in a slight shift of the population to a lower abundance of the β‐proteobacteria.

Disinfection is mandatory for swimming pools: public pools are usually disinfected by gaseous chlorine or sodium hypochlorite and cartridge filters; home pools typically use stabilized chlorine. These methods produce a variety of disinfection byproducts (DBPs), such as trihalomethanes (THMs), which are regulated carcinogenic DBPs in drinking water that have been detected in the blood and breath of swimmers and of nonswimmers at indoor pools. Also produced are halogenated acetic acids (HAAs) and haloketones, which irritate the eyes, skin, and mucous membranes; trichloramine, which is linked with swimming-pool-associated asthma; and halogenated derivatives of UV sun screens, some of which show endocrine effects. Precursors of DBPs include human body substances, chemicals used in cosmetics and sun screens, and natural organic matter. Analytical research has focused also on the identification of an additional portion of unknown DBPs using gas chromatography (GC)/mass spectrometry (MS) and liquid chromatography (LC)/MS/MS with derivatization. Children swimmers have an increased risk of developing asthma and infections of the respiratory tract and ear. A 1.6-2.0-fold increased risk for bladder cancer has been associated with swimming or showering/bathing with chlorinated water. Bladder cancer risk from THM exposure (all routes combined) was greatest among those with the GSTT1-1 gene. This suggests a mechanism involving distribution of THMs to the bladder by dermal/inhalation exposure and activation there by GSTT1-1 to mutagens. DBPs may be reduced by engineering and behavioral means, such as applying new oxidation and filtration methods, reducing bromide and iodide in the source water, increasing air circulation in indoor pools, and assuring the cleanliness of swimmers. The positive health effects gained by swimming can be increased by reducing the potential adverse health risks.

A series of polyaluminum chloride sulfate (PACS) coagulants, which have different SO 2 4 /Al 3+ and OH/Al (y) mole ratio, has been successfully developed using AlCl 3 ·6H 2 O, Al 2 (SO 4 ) 3 ·18H 2 O and Na 2 CO 3 as raw materials. The coagulation performance of PACS for removing natural organic matter (NOM) from surface water was evaluated, and the effect of SO 2- 4 /Al 3+ mole ratio and y value in coagulants PACS on DOC and UV 254 removal was determined. Furthermore, the influence of pH and dosage of the selected PACS with a SO 2- 4 /Al 3+ ratio of 0.0664 and a y value of 2.0, which achieved the best coagulation performance for the removal of DOC and UV 254 of all PACS coagulants, on the removal of DOC and UV 254 and residual aluminum concentration in treated water was investigated. The results were compared with the ones of polyaluminum chloride (PAC) with y value of 2.0. The experimental data show that the performance of PACS as a coagulant was highly dependent on SO 2- 4 /Al 3+ mole ratio and y value. Both for the selected PACS and for PAC, the best DOC and UV 254 removal results were obtained in the range of pH from 5.0 to 8.2 and at the coagulation dose of 5.0 mg/L as Al. Under the optimum coagulation conditions, the selected PACS gave higher DOC and UV 254 removal efficiencies, and lower residual aluminum concentrations in the treated water than PAC. The maximum removal of DOC and UV 254 for PACS was approximately 88.0% and 93.0%, respectively. At the optimum coagulant dose and pH 6.5, the concentration of residual aluminum in treated water by both selected PACS and PAC can comply with the regulated limits. The major mechanisms of NOM removal by PACS and PAC coagulation involve complexation-charge-neutralization-precipitation.

With the Water Framework Directive (WFD) the European Commission (EC) is requested to define environmental quality standards for pollutants to protect aquatic life in surface waters. Quality standards have to be derived by a scientific risk assessment and should not be exceeded. The recommended quality standards are mainly based on long term toxicological tests with algae, crustaceans and fish. The lowest effect concentration is divided by an assessment factor between 10 and 1000, which considers the data quality and quantity. In this work funded by the German Lander Working Party on Water (Landerarbeitsgemeinschaft Wasser – LAWA) environmental quality standards for 40 considered relevant substances were derived for aquatic ecosystems. The data sheets cover the identification of the compounds, their behaviour in the environment (physical-chemical properties, biotic and abiotic degradation, sorption, bioaccumulation), information about mode of action, uses, analytical determination and available quality criteria. Ecotoxicological effect concentrations for bacteria, algae, protozoa, aquatic plants, crustaceans, fish, amphibians, insects and molluscs are listed. For 17 of the 40 hazardous substances investigated, quality objectives above 1 μg/L were derived. For 12 substances the values were between 0.1 μg/L and 1 μg/L and for 5 substances lower than 0.1 μg/L. Incomplete ecotoxicological data sets of the remaining compounds do not allow the derivation of quality standards. Especially for drugs further ecotoxicological test results are needed. Mit der Wasserrahmenrichtlinie (WRRL) sollen fur einzelne potenziell flussgebietsspezifisch relevante Schadstoffe europaweit sogenannte Umweltqualitatsnormen festgelegt werden, um einen guten Gewasserzustand zu erreichen. Diese Qualitatsnormen werden durch eine wissenschaftliche Bewertung des Risikos abgeleitet und durfen aus Grunden des Gesundheits- und Umweltschutzes nicht uberschritten werden. Im Rahmen eines von der Landerarbeitsgemeinschaft Wasser (LAWA) geforderten Forschungsprojektes wurden fur 40 potenziell flussgebietsspezifisch relevante Stoffe Qualitatsnormen zum Schutz aquatischer Lebensgemeinschaften in Oberflachengewasser vorgeschlagen. Ziel dieser Arbeiten ist es, eine Bewertungsgrundlage fur gewasserrelevante Stoffe zu schaffen. Die Ableitung der Umweltqualitatsnorm-Vorschlage folgen dem von der WRRL vorgegebenen Verfahren. Sie beruht auf Toxizitatsdaten aus langerfristigen oder akuten Wirkungstests vor allem fur die Organismengruppen der Algen, Kleinkrebse und Fische. In Abhangigkeit von der Datenlage wird der niedrigste valide Toxizitatswert durch einen Sicherheitsfaktor dividiert, der zwischen 10 und 1000 liegt. Von den betrachteten 40 Substanzen wurden fur 17 Stoffe Qualitatsnorm-Vorschlage oberhalb einer Konzentration von 1 μg/L berechnet. Bei 12 Stoffen liegt der Wert zwischen 0.1 μg/L und 1 μg/L und bei 5 Stoffen unter 0.1 μg/L. Fur einige Stoffe, insbesondere fur Arzneimittelwirkstoffe, konnten aufgrund fehlender okotoxikologischer Daten keine Qualitatsnorm-Vorschlage abgeleitet werden. Hier sind noch weitere Untersuchungen notig, um eine sichere Datenbasis zu erreichen.

Interactions between dissolved organic substances (dissolved organic matter and two model substances), ions (Na + and Ca 2+ ) and the membrane surface were investigated using a submerged membrane module. The membrane permeability, the fouling formation and the rejection were significantly influenced by the solution’s ionic strength and especially by the presence of calcium ions. An increase of the ionic strength led to a decrease of the DOMrejection of the membrane from 75% to about 50% if Na + -ions were added and to about 15% if Ca 2+ -ions were added. This was due to neutralization of charges of the membrane surface and due to shielding of negative charges of DOM molecules. The ionic strength and pH of the cation solutions were kept at similar values. As the solution ionic strength increases, DOM molecules can permeate more easily through the membrane pores, since their shape and molecular size change. Adsorption of DOM on the membrane surface and in the membrane pores was only observed by filtration of solutions with Ca 2+ . The results showed that in the presence of Ca 2+ , adsorption played a mayor role in flux decline and fouling formation.

The effect of different organic and inorganic aqueous matrices on the photocatalytical degradation of dissolved atrazine and dichloroacetic acid (DCA) with immobilized TiO 2 was investigated. Two series of experiments were carried out at pH values around 7.1 for the degradation of atrazine and around 5.3 for the degradation of DCA. It is shown that the effects of the water constituents are completely different for the various substances and pH ranges. In pure deionized water 95% of the initial amount p = 1 mg/L of atrazine were degraded within 24 hours. Tap water as matrix led to a distinct lower degradation rate (factor 3). The single additives chloride, sulfate, phosphate, carbonate and DOC showed no decrease in the degradation rate. Especially in the case of phosphate and carbonate there was even a significant promoting effect. DEDIA, the doubly desalkylated and not dechlorinated product, occurred in higher concentrations than in the experiment without additives. In pure deionized water ρ 0 (DCA) = 1 mg/L was completely degraded within 330 min. By addition of any tested substance, organic or inorganic, the degradation rate of DCA, which is strongly dependent on the adsorption on the TiO 2 surface, decreased clearly. In the case of tap water the degradation rate decreased by a factor of 7.5. From the checked inorganic ions phosphate showed the strongest effect followed by sulfate, chloride and carbonate. Added DOC also had a significant influence on the degradation rate.

Various leaching experiments applied to municipal waste incineration ash were compared in order to find the best available procedure to measure the total mass flow caused by natural leaching (source strength) of the material. The results of various batch experiments and two different laboratory column experiments run under water-saturated conditions were compared with water-unsaturated field-scale column experiments (lysimeter). The results of the batch experiments were not transferable to the column and field experiments. But, very good accordance could be observed between the breakthrough curves of the two column experiments conducted in the laboratory under water-saturated conditions and the water-unsaturated field-scale columns, with few exceptions. The results show that batch experiments are not sufficient to predict the source strength and its changes over time. Instead, column experiments are essential for a realistic risk assessment. For most inorganic parameters, a laboratory column experiment lasting less than 5 days is sufficient for a risk assessment in the foreseeable future.

Ozonation is a treatment step which was first applied in the 1960s in pool water treatment for disinfection as well as for oxidation of pool water contaminants. Contact time between ozone and pool water was identified to be of significance with an increased elimination efficiency regarding chloramines, trihalogenmethane formation potential and the permanganate index for longer reaction times. Oxidation via OH radicals might be the dominating pathway. In this study ozonation was compared with the ozone based advanced oxidation processes ozone/UV and ozone/hydrogen peroxide regarding the elimination efficiency of both disinfection by-products (DBPs) and DBP precursors. It was observed that AOPs in comparison to ozonation showed an increased elimination efficiency regarding total organic carbon (TOC), the organically bound halogens adsorbable on activated carbon (AOX) and AOX formation potential. A contact time of 3 minutes between pool water and oxidant turned out to be practically sufficient. Just for the trihalomethane (THM) formation potential ozonation showed a slight advantage compared to the AOPs because ozonation is a highly selective oxidant and OH radical reactions are known to produce small reactive molecules which are easier transformed to THMs. Combination of membrane filtration and AOPs resulted in an elimination of 10 to 90 % of the DBPs and their precursors. The ozone/hydrogen peroxide process is suggested for pool water treatment because of the higher elimination rates compared to ozonation and of economic reasons compared to the ozone/UV process.

In this work a coupling method for the characterisation of colloid-mediated transport of the metal(loid) species in porous media was developed. For this transport experiments quartz sand was used as column packing material and the synthetic three-layer clay mineral laponite as model colloid. The determination of colloids was conducted by means of UV detection. The quantification of the metal(loid) ions was carried out in two different ways: (1) The fractions collected at the column outlet were analysed with an inductively coupled plasma mass spectrometer (ICP-MS) (offline measurements); (2) the column system was directly coupled with ICP-MS (online measurements). In the column experiments the influence of laponite colloids on the transport of Cu, Pb, Zn, Pt and As species was investigated. In the offline experiments as a consequence of dilution during sample preparation no metal(loid) species at the column outlet could be found. Unlike this the breakthrough of all metal(loid)s could be detected under the same experimental column conditions in the coupling experiments. This coupling technique offers the online detection of the metal species and colloidal particles with high resolution even at low concentrations and without any time-consuming preparation. The coupling experiments have shown that the laponite particles accelerate the transport of the cationic metals. For anionic metal(loid) species no influence of laponite on their transport behaviour was found. Kopplung einer Saulenanlage mit ICP-MS fur die Charakterisierung des kolloidgetragenen Metall(oid)-Transports in porosen Medien In dieser Arbeit wurde fur die Charakterisierung des kolloidalen Transports von Metall(oid)en in porosen Medien eine Kopplungstechnik entwickelt. In den Transportexperimenten diente Quarzsand als Fullmaterial fur die Saule und das synthetisch hergestellte Dreischicht-Tonmineral Laponit als Modellkolloid. Die Aufnahme der Durchbruchskurven von Kolloiden erfolgte mit Hilfe eines UV-Detektors. Die Quantifizierung von Metall(oid)-Ionen wurde auf zwei unterschiedliche Weisen durchgefuhrt: (1) Die am Saulenausgang gesammelten Fraktionen wurden mit einem Massenspektrometer mit induktiv gekoppeltem Plasma (ICP-MS) analysiert; (2) die Saulenanlage wurde direkt mit dem ICP-MS-System gekoppelt. In den Saulenexperimenten wurde der Einfluss des Laponits auf den Transport der Cu-, Pb-, Zn-, Pt- und As-Spezies untersucht. Als Folge der Verdunnung bei der Probenvorbereitung konnten in den Offline-Experimenten am Saulenausgang keine Metall(oid)-Spezies gefunden werden. Im Gegensatz dazu konnten in den Kopplungsexperimenten bei den gleichen Saulenbetriebsbedingungen die Durchbruchskurven fur alle Metall(oid)e aufgenommen werden. Die Kopplungstechnik ermoglicht die Online-Detektion der Metallspezies und der Kolloide bei niedrigen Konzentrationen mit hoher Auflosung und ohne zeitaufwandige Probenvorbereitung. Die Kopplungsexperimente haben gezeigt, dass die Laponitkolloide den Transport kationischer Metalle beschleunigen. Ein Einfluss von Laponit auf den Transport der anionischen Metall(oid)e wurde nicht festgestellt.

Environmentally relevant polar persistent organic pollutants (pharmaceuticals and diagnostic agents) were chosen according to human consumption and occurrence in the aquatic environment (sewage plant effluents, rivers and groundwater) to investigate their behavior during photocatalytic oxidation. From data compilation in the literature, the active metabolite clofibric acid of some lipid lowering agents, the anti-epileptic drug carbamazepine and the X-ray contrast media iomeprol were selected. The degradation of the persistent pollutant was monitored by HPLC/DAD/FLD. The study also focuses on the identification and quantification of possible degradation products by HPLC/DAD/FLD and HPLC/MS/MS. The degradation process was also monitored by determination of sum parameters and inorganic ions. Various aromatic and aliphatic degradation products have been identified and quantified. From analytical data, a possible degradation scheme for carbamazepine was proposed. Kinetic studies showed that the TiO2 photocatalyst P25 was more active in clofibric acid degradation than Hombikat UV100. For photocatalytic degradation of iomeprol Hombikat UV100 was more suitable than P25. In general the presence of NOM and carbamazepine retarded the photocatalysis of clofibric acid. Radiation attenuation, competition for active sites and surface deactivation of the catalyst by adsorption are the reason for that. The results of this work proof that photocatalysis is a promising technology to reduce persistent substances even if they are present in low concentrations or in a complex matrix.

The combination of semiconductor photocatalysis with cross-flow microfiltration accompanied by periodical back-washing was investigated in a pilot plant. The investigation included the testing of membrane materials because the membrane must resist the abrasion and the periodical back-washing. Another objective of this investigation was to assess the potential of two different TiO(2) materials (Hombikat UV100 and P25) for continuous photocatalytic degradation of persistent organic pollutants. The study focused on the long-term stability of the photocatalytic activity of TiO(2) during its continuous application. The combination of photocatalysis and cross-flow microfiltration allowed the separation and reuse of TiO(2) after the photocatalytic degradation of clofibric acid, carbamazepine and iomeprol. The investigations showed that the photocatalytic activity of P25 and Hombikat UV100 was constant during continuous usage over several days. This study indicates the high potential of the combination of heterogeneous photocatalytic oxidation processes with cross-flow microfiltration accompanied by periodical back-washing of the membrane. Thus environmentally relevant pharmaceuticals and X-ray contrast media can be transformed and mineralized in a continuous water treatment process.